The Nervous SystemThe Nervous System

Nervous systemNervous system

One of the two main communication systems in One of the two main communication systems in the body the body

Coordinates all the activities of the body carrying Coordinates all the activities of the body carrying messages from one cell to the nextmessages from one cell to the next

Enables the body to respond and adapt to Enables the body to respond and adapt to changes that occur inside and outside the bodychanges that occur inside and outside the body

Basic structural unit is the NEURON or nerve Basic structural unit is the NEURON or nerve cellcell

The Nervous SystemThe Nervous SystemEach neuron Each neuron

consists of:consists of:The cell body.The cell body.Dendrites.Dendrites.The axon. The axon.

Neurons Neurons

Cell body consists of nucleusCell body consists of nucleusDendrites consist of nerve fibers that carry Dendrites consist of nerve fibers that carry

impulses toward the cell bodyimpulses toward the cell bodyAxon is a single nerve fiber that carries Axon is a single nerve fiber that carries

impulses away from the cell bodyimpulses away from the cell bodyMyelin sheath covers the axon (fat covering) Myelin sheath covers the axon (fat covering)

that insulates and maintains the axonthat insulates and maintains the axonNodes of Ranvier are areas where no myelin Nodes of Ranvier are areas where no myelin

is presentis present

The axon of one neuron lies next to the The axon of one neuron lies next to the dendrites of another neurondendrites of another neuron

The spaces between them are called The spaces between them are called synapsessynapses

Impulses coming from one axon “jump” the Impulses coming from one axon “jump” the synapse to get to the dendrite of another synapse to get to the dendrite of another neuron which carry it in the right directionneuron which carry it in the right direction

Special chemicals, neurotransmitters, Special chemicals, neurotransmitters, found at the end of each neuron allow found at the end of each neuron allow impulses to pass from one neuron to impulses to pass from one neuron to another so impulses can follow many another so impulses can follow many different routesdifferent routes

Nerve fibersNerve fibersNerves are a combination of many nerve Nerves are a combination of many nerve

fibers found in the brain and spinal cordfibers found in the brain and spinal cord3 types:3 types:

Afferent – sensory nervesAfferent – sensory nervesNerves carry messages from body to the brain and Nerves carry messages from body to the brain and

spinal cordspinal cordEfferent – motor nervesEfferent – motor nerves

carries messages from the brain and spinal cord to carries messages from the brain and spinal cord to the bodythe body

Associative - interneuronsAssociative - interneuronsCarries impulses from the sensory neuron to the Carries impulses from the sensory neuron to the

motor neuronmotor neuron

3 Divisions 3 Divisions Central nervous systemCentral nervous system

BrainBrainSpinal cordSpinal cord

Peripheral nervous systemPeripheral nervous systemNervesNervesAutonomic nervous systemAutonomic nervous system

Controls involuntary body functionsControls involuntary body functions

Autonomic nervous systemAutonomic nervous systemIncludes peripheral nerves and ganglia (group of Includes peripheral nerves and ganglia (group of

cell bodies outside the CNS that carry impulses to cell bodies outside the CNS that carry impulses to involuntary muscles and glands)involuntary muscles and glands)

Central nervous systemCentral nervous systemBRAIN – mass of nerve tissue protected BRAIN – mass of nerve tissue protected

by membranes and skullby membranes and skullCerebrum Cerebrum

Largest and highest sectionLargest and highest sectionHas convolutions (folds) that separates the lobesHas convolutions (folds) that separates the lobes4 lobes:4 lobes:

FrontalFrontal ParietalParietal TemporalTemporal OccipitalOccipital

Frontal lobeFrontal lobe

Links all components of behaviorsLinks all components of behaviors Impulse controlImpulse control Injury here may cause lose of function on Injury here may cause lose of function on

one side of the bodyone side of the body Speech may become halted or disorganizedSpeech may become halted or disorganized Personality changes can occurPersonality changes can occur Social rules are disregardedSocial rules are disregarded Sustained attention and “insight” are affectedSustained attention and “insight” are affected

Temporal lobeTemporal lobe

Perceives and recognizes verbal materialPerceives and recognizes verbal material Most commonly injuredMost commonly injured Causes misunderstandings in what is saidCauses misunderstandings in what is said Emotional changes such as unexplained Emotional changes such as unexplained

panic or tearfulness can occurpanic or tearfulness can occur Left temporal lobe involved in production of Left temporal lobe involved in production of

speech, naming and verbal memoryspeech, naming and verbal memory Right temporal lobe involves musical ability, Right temporal lobe involves musical ability,

foreign language, visual memory and foreign language, visual memory and comprehension of the environmentcomprehension of the environment

Parietal lobeParietal lobe Construction of languageConstruction of language Recall of long term memories may be mixed Recall of long term memories may be mixed

up in time and sequencingup in time and sequencing Easily lost or confused about left/rightEasily lost or confused about left/right Difficulty recognizing and naming what they Difficulty recognizing and naming what they

seesee May affect ability to read, write or perform May affect ability to read, write or perform

calculationscalculations Conscious sensation and voluntary Conscious sensation and voluntary

movement is affectedmovement is affected Injury to front part of the lobe may cause loss Injury to front part of the lobe may cause loss

of body sensationof body sensation

Occipital lobeOccipital lobe

Injury usually results in blindness to part or Injury usually results in blindness to part or all of the visual fieldall of the visual field

People may experience “blind spots” or People may experience “blind spots” or “holes”“holes”

May misperceive pictures they seeMay misperceive pictures they seeRecognition of colors may be distortedRecognition of colors may be distorted

Main functioning unit of the Main functioning unit of the nervous system is the neuronnervous system is the neuron

A.) TrueA.) True

B.) FalseB.) False

Lobe that controls hearing & is Lobe that controls hearing & is most often injuredmost often injured

A.) FrontalA.) Frontal

B.) ParietalB.) Parietal

C.) TemporalC.) Temporal

D.) OccipitalD.) Occipital

Lobe that controls visionLobe that controls vision

A.) FrontalA.) Frontal

B.) ParietalB.) Parietal

C.) TemporalC.) Temporal

D.) OccipitalD.) Occipital

Lobe that controls long term Lobe that controls long term memorymemory

A.) FrontalA.) Frontal

B.) ParietalB.) Parietal

C.) TemporalC.) Temporal

D.) OccipitalD.) Occipital

Lobe that coordinates all behaviorsLobe that coordinates all behaviors

A.) FrontalA.) Frontal

B.) ParietalB.) Parietal

C.) TemporalC.) Temporal

D.) OccipitalD.) Occipital

CerebellumCerebellum Below cerebrumBelow cerebrum Responsible for Responsible for

muscle coordination, muscle coordination, balance and posture, balance and posture, muscle tonemuscle tone

DiencephalonDiencephalon Section between the cerebrum and midbrainSection between the cerebrum and midbrain Contains 2 structuresContains 2 structures

Thalamus – acts as a relay center and directs sensory Thalamus – acts as a relay center and directs sensory impulses to the cerebrumimpulses to the cerebrum

Hypothalamus – regulates and control the autonomic Hypothalamus – regulates and control the autonomic nervous system, temperature, appetite, water balance, nervous system, temperature, appetite, water balance, sleep, etc. Also involved in emotions such as fear, sleep, etc. Also involved in emotions such as fear, anger, pleasure, pain and affectionanger, pleasure, pain and affection

Midbrain Midbrain Below the cerebrum and top of the brain stemBelow the cerebrum and top of the brain stemResponsible for conducting impulses between Responsible for conducting impulses between

brain parts and certain eye and auditory brain parts and certain eye and auditory reflexesreflexes

Pons Pons Below the midbrain and in the brain stemBelow the midbrain and in the brain stemResponsible for conducting messages to Responsible for conducting messages to

other parts of the brain, chewing, tasting, other parts of the brain, chewing, tasting, saliva production and assists with breathingsaliva production and assists with breathing

Medulla oblongataMedulla oblongataLowest part of the brain stemLowest part of the brain stemConnects with the spinal cord and is Connects with the spinal cord and is

responsible for breathing, heartbeat, responsible for breathing, heartbeat, swallowing, coughing and blood pressureswallowing, coughing and blood pressure

Spinal cordSpinal cord Continues down from the medulla Continues down from the medulla

oblongata oblongata Ends at the first or second lumbar Ends at the first or second lumbar

vertebraevertebrae Surrounded and protected by Surrounded and protected by

vertebraevertebrae Responsible for many reflex actions Responsible for many reflex actions

and carrying afferent and efferent and carrying afferent and efferent nervesnerves

Meninges Meninges 3 membranes that cover and protect 3 membranes that cover and protect

the brain and spinal cordthe brain and spinal cordDura mater – outer layerDura mater – outer layerArachnoid membrane – middle, delicate Arachnoid membrane – middle, delicate

layerlayerPia mater – attached to the brain and Pia mater – attached to the brain and

contains blood vessels that nourish the contains blood vessels that nourish the nerve tissuenerve tissue

The brain has 4 ventricles The brain has 4 ventricles (hollow spaces that (hollow spaces that connect with each other connect with each other and the space under the and the space under the arachnoid membrane)arachnoid membrane)

Filled with fluid called Filled with fluid called cerebrospinal fluidcerebrospinal fluidCirculates continuouslyCirculates continuouslyServes as shock absorber Serves as shock absorber

to protect brain and spinal to protect brain and spinal cordcord

Carries nutrients to parts of Carries nutrients to parts of the CNS and helps remove the CNS and helps remove waste productswaste products

Peripheral Nervous SystemPeripheral Nervous System

Consists of the somatic and autonomic Consists of the somatic and autonomic nervous systemsnervous systems

Somatic nervous systemSomatic nervous system12 pairs of cranial nerves12 pairs of cranial nerves31 pairs of spinal nerves31 pairs of spinal nerves

Spinal nerves carry messages to and from Spinal nerves carry messages to and from the spinal cord and are mixed nerves (both the spinal cord and are mixed nerves (both afferent and efferent)afferent and efferent)

Autonomic Nervous SystemAutonomic Nervous System

Branch of peripheral nervous systemBranch of peripheral nervous systemMaintains balance in the involuntary Maintains balance in the involuntary

functions of the body and allows the body functions of the body and allows the body to react in times of emergencyto react in times of emergency

2 divisions:2 divisions:SympatheticSympatheticParasympatheticParasympatheticWork together to maintain homeostasisWork together to maintain homeostasis

In times of emergency the sympathetic In times of emergency the sympathetic nervous system prepares the body to actnervous system prepares the body to act Increased heart rateIncreased heart rate Increased respirationsIncreased respirations Increased blood pressureIncreased blood pressureDecreased digestionDecreased digestion

After the emergency, the parasympathetic After the emergency, the parasympathetic nervous system counteracts actions of the nervous system counteracts actions of the sympathetic nervous systemsympathetic nervous systemDecreased heart rateDecreased heart rateDecreased respirations, etc.Decreased respirations, etc.

Diseases/disordersDiseases/disorders Traumatic disorders – caused by injury:Traumatic disorders – caused by injury:

Concussion.Concussion. Brain contusion.Brain contusion.

Congenital disordersCongenital disorders – present at birth: – present at birth: Spina bifida.Spina bifida. Hydrocephalus.Hydrocephalus. Cerebral palsy.Cerebral palsy. Cerebrovascular accident (CVA).Cerebrovascular accident (CVA). Encephalitis.Encephalitis. Epilepsy.Epilepsy. Meningitis.Meningitis. Multiple sclerosis (MS)Multiple sclerosis (MS) Neuralgia.Neuralgia. Paralysis.Paralysis. Parkinson’s disease.Parkinson’s disease. Dementia.Dementia. Alzheimer’s disease.Alzheimer’s disease.

Spina BifidaSpina Bifida Opening in the spinal Opening in the spinal

column column At delivery, spinal cord At delivery, spinal cord

and nerves are exposed and nerves are exposed causing nerve damagecausing nerve damage

Results in paralysisResults in paralysis

Cerebral PalsyCerebral Palsy

Caused by brain damage at birthCaused by brain damage at birthLack of oxygen, birth injuries, infection, etc.Lack of oxygen, birth injuries, infection, etc.Symptoms:Symptoms:

Tense muscles leading to Tense muscles leading to contracturescontracturesTremorsTremorsMental retardationMental retardation

Treatment:Treatment:Therapy, anticonvulsants, braces, surgeryTherapy, anticonvulsants, braces, surgery

Cerebrovascular accident (CVA)Cerebrovascular accident (CVA)

a.k.a. strokea.k.a. stroke Blood flow to the brain is Blood flow to the brain is

impaired resulting in brain tissue impaired resulting in brain tissue damagedamage

CausesCauses Cerebral hemorrhageCerebral hemorrhage AneurysmAneurysm Weak blood vesselsWeak blood vessels Blood clotBlood clot

Treatment depends on causeTreatment depends on cause

Encephalitis Encephalitis

Inflammation of the brain resulting in Inflammation of the brain resulting in weakness, visual disturbances, vomiting, weakness, visual disturbances, vomiting, stiff neck and back, comastiff neck and back, coma

Caused Caused VirusVirusChemicalChemicalBacteriaBacteria

Treatment is supportive including Treatment is supportive including medications and monitoringmedications and monitoring

Epilepsy Epilepsy Seizure syndromeSeizure syndromeDisorder associated with abnormal Disorder associated with abnormal

electrical impulses in the neurons of the electrical impulses in the neurons of the brainbrain

CausesCausesTraumaTraumaToxinsToxins Idiopathic (spontaneous)Idiopathic (spontaneous)

Treated with medicationsTreated with medications

Hydrocephalus Hydrocephalus

Excessive accumulation Excessive accumulation of cerebrospinal fluid in of cerebrospinal fluid in the ventriclesthe ventricles

Symptoms include Symptoms include abnormally large head, abnormally large head, prominent forehead, prominent forehead, irritability, retardationirritability, retardation

Treated with Treated with

surgical shunt surgical shunt

between ventriclesbetween ventricles

Meningitis Meningitis

Inflammation of the meninges Inflammation of the meninges of the brain and/or spinal cordof the brain and/or spinal cord

Caused by bacteria or virusCaused by bacteria or virus High fever, headaches, back High fever, headaches, back

and neck pain, n/v, delirium, and neck pain, n/v, delirium, convulsions and deathconvulsions and death

Treatment includes Treatment includes medications and medications and anticonvulsantsanticonvulsants

Multiple sclerosisMultiple sclerosis Chronic, progressive Chronic, progressive

disabling condition disabling condition resulting from resulting from degeneration of the degeneration of the myelin sheathmyelin sheath

Occurs between 20 and Occurs between 20 and 40 y.o.40 y.o.

Cause is unknownCause is unknown Progresses at different Progresses at different

rates depending on the rates depending on the personperson

No cureNo cure

Neuralgia Neuralgia

Nerve painNerve painCaused by inflammation, pressure, toxins Caused by inflammation, pressure, toxins

and other diseaseand other diseaseTreatment directed at eliminating the Treatment directed at eliminating the

cause of the paincause of the pain

Paralysis Paralysis

Usually results from brain or Usually results from brain or spinal cord injuryspinal cord injuryHemiplegiaHemiplegia

Paralysis on one sideParalysis on one side

Quadriplegia Quadriplegia Paralysis of the arms, legs, and Paralysis of the arms, legs, and

body below the spinal cord injurybody below the spinal cord injury

No cure, treatment is No cure, treatment is supportivesupportive

Parkinson’s diseaseParkinson’s disease

Chronic, progressive Chronic, progressive degeneration of brain cells degeneration of brain cells usually in people over 50 y.o.usually in people over 50 y.o.

Tremors, stiffness, muscular Tremors, stiffness, muscular rigidity, forward leaning rigidity, forward leaning position, shuffling gait, mood position, shuffling gait, mood swings, etc.swings, etc.

Treatment is supportive and Treatment is supportive and symptomaticsymptomatic

Shingles Shingles

Herpes zosterHerpes zoster Inflammation of nerve cells caused by Inflammation of nerve cells caused by

herpes virusherpes virusSame virus that causes chicken poxSame virus that causes chicken poxOccurs in thoracic area on one side of the Occurs in thoracic area on one side of the

body and follow path of affected nervesbody and follow path of affected nerves Itching, fever, increased skin sensitivityItching, fever, increased skin sensitivityTreatment is to relieve pain and itching Treatment is to relieve pain and itching

until inflammation subsidesuntil inflammation subsides

DementiaDementia

General term defining a loss in at least two General term defining a loss in at least two areas of complex behavior such as areas of complex behavior such as language, memory, visual/spatial abilities language, memory, visual/spatial abilities or judgmentor judgment

Does not mean that everyone that is Does not mean that everyone that is forgetful has dementiaforgetful has dementia

Alzheimer’s diseaseAlzheimer’s disease

Progressive disease where initial symptom is usually a Progressive disease where initial symptom is usually a problem with remembering recently learning informationproblem with remembering recently learning information

Nerve endings in the cortex of the brain degenerate and Nerve endings in the cortex of the brain degenerate and block signalsblock signals

Cause is unknown and has 3 stages:Cause is unknown and has 3 stages: 11stst stage lasts 2-4 years and involves short-term memory loss, stage lasts 2-4 years and involves short-term memory loss,

anxiety and poor judgmentanxiety and poor judgment 22ndnd stage lasts 2-10 years and increases memory loss, difficulty stage lasts 2-10 years and increases memory loss, difficulty

recognizing people, motor problems, loss of social skillsrecognizing people, motor problems, loss of social skills 33rdrd stage lasts 1-3 years and includes inability to recognize self, stage lasts 1-3 years and includes inability to recognize self,

weight loss, seizures, mood swings, and aphasia (loss of weight loss, seizures, mood swings, and aphasia (loss of speech).speech).